Separation of ammonium chloride and aliphatic amine hydrochlorides from mixtures of the same with copper chloride



Patented Mar. 13, 1945 SEPARATION OF AMMONIUM CHLORIDE AND ALIPHATICAMINE HYDROCHLO- RIDES FROM MIXTURES OF THE SAME WITH COPPER CHLORIDENoland Poifenberger and Ray D. Holmes, Midland, Mich.,- assignors to TheDow Chemical; Company, Midland, Mich, a corporation of Michigan I NoDrawing. Application February 14, 1944,

a Serial No. 522,390

16 Claims. (0]. 23-100) This invention relates to a method of recoveringammonium chloride and/or aliphatic amine hydrochlorides and particularlyto the recovery of the same from solutions containing copperchloride.This application is a continuation-inpart of and a substitute for ourcopending application, Serial No. 412,834, filed September 29,

Ammonium chloride and aliphatic amine hydrochlorides are frequentlyprepared industrially by combining ammonia or an aliphatic amine withhydrochloric acid. In addition, these compounds are formed incidentallyto the manufacture of other products in some industrial processes. Insome such cases they can be isolated in the form of an aqueous solutionfrom which they can be recovered easily. In other processes, however,solutions of ammonium chloride together with copper chloride areobtained in large quantities. Such solutions have not heretofore tialconcentration of ammonia or alkyl amine in the freestate. Accordingly,ammonia or alkyl been economical as sources for pure ammonia chloridedue'to the lack. of a practical method for separating the copperchloride from the ammonium chloride. The. solutions have usually beentreated with alkalies, e. g.. sodium hydroxide, to liberate ammonia andleave the copper as an insoluble oxide or hydroxide, or electrolyzed torecover metallic copper, or they have, in some instances, been treatedwith a sulfide such as hydrogen sulfide or ammonium sulfide toprecipitate the copper as the sulfide. The first of these methods isdisadvantageous in that it involves the consumption of alkali andresults in destrucmonium or aliphatic amine hydrochloride. The monoarylamine may be used either in the form of the free base or as thehydrochloride. The" .'cess of the monoaryl amine, particularly when thelatter is used as the free base, is separated. The remaining aqueoussolution, containing the ammonium chloride or aliphatic aminehydrochloride, may be further treated in a suitable manner, e. g., withammonium sulfide, to remove any remaining traces of copper and then beeither crystallized or evaporated to' recover substantially pureammonium chloride or amine hydrochloride. The complex compound of copperchloride with the aryl amine does not form readily when the reactionmixture contains a substanamine if present in free form and inappreciable amount in the solution of the ammonium chloride and coppercompound is removed, e. g., by

be used to separate the copper chloride from the ammonium chloride orlower aliphatic amine hydrochloride, it will be particularly describedwith reference to the recovery of ammonium chloride separate the copperchloride and said hydro-M chloride from one another.

This invention whereby the foregoing object is accomplished comprisesbringing an aqueous solution' containing ammonium chloride and/or analiphatic amine hydrochloride and a copper chloride into contact with amonoaryl amine such as aniline, ortho-toluidine, para-toluidine,dimethylaniiine, monomethylaniline; alpha-naphthylamine, etc., underconditions such that the copper chloride reacts with the monoaryl amineto form .a complex compound which is substandaily insoluble in theaqueous solution of the am- .5

and the use of aniline to eflect the separation. This is only by way ofexample and not by way a of limitation.

The reaction between the copper chloride, in which the copper may bepresent in the cuprous orthe cupric state. or in both, and the anilineis preferably carriedout by agitating together the of copper removalthus obtained will not ordi- W y Justify the espouse of recovering menlow 60* 0., but above the point at which am monium chloride crystallizesfrom the solution. For convenience this lower temperature is hereinafterreferred to as the crystallizing temperature. However, still lowertemperatures may be employed, in which case it may be advantageous towash, or otherwise treat, the separated complex compound to free it fromcrystals of ammonium chloride. The distribution of the copper betweenthe aqueous and the aqueous-immiscible portions of the mixture varieswith the temperature. At higher temperatures more of the copper isretained inthe aqueous portion than at lower temperatures. Agitation ofthe mixture may be continued until the reaction has attained the desireddegree of completion. This usually requires only a few minutes, e. g.,from one to ten minutes, although the time depends somewhat upon theefficiency of the agitation. Inert organic liquids immiscible with theaqueous ammonium chloride, such as benzene or chlorobenzene, may also beadded to the mixture in order to facilitate formation and separation ofthe mixture into layers. Both cupric and cuprous chlorides will reactwith aniline in the above manner to form complex compounds which aresubstantially insoluble in the ammonium chloride solution. However, inseparating cuprous'chloride from ammonium chloride, it may be desirableto carry out the reaction in the absence of oxygen or other oxidizingagent, e. g., under vacuum or Example 1 1085 grams of an aqueoussolution containing 52 grams (0.52 mol) of cuprous chloride and 165grams (3.01 mols) of ammonium chloride is treated, in the absence ofair, with 50 grams (0.53 mol) of aniline and 50 grams of benzene, and

the mixture agitated vigorously at room temperature for two minutes.Upon standing, the mature forms into an oily layer and an'aqueous layer,which are separated. The aqueous layer is further treated twice in asimilar manner with 100 -gram portions of aniline and benzene. The

, three portions of "aniline are combined and steamsmall amount ofcopper sulfide thus precipitated in-contact with a non-oxidizingatmosphere, to

prevent oxidation or the cuprous copper.

After the reaction is complete -the oilyaniline layer is separated fromthe aqueous layer in any suitable manner, e. g., by decantation orsettling. Filtration may be resorted to in case crystals or lumps ofthercomplex compound are present.

The oily or solid product which contains the complex compound may thenbe treated in any of several ways for recovery of the aniline and thecopper chloride, e. g., by heating to volatilize the aniline and leavethe copper chloride as a residue.

vigorously with 40 grams (0.425 mol) of aniline solved copper chloridewhich it is not economical monium sulfide may be added to precipitatethe copper as copper sulfide. However, the order of these operations maybe varied, e. g., the dissolved copper may be precipitated with ammoniumsulflde prior to removal of the aniline or, if desired, prior todecomposition of the aniline hydrochloflde so formed, the solution maybe treated with ride. After illtrationto remove the copper suldistilleduntil the benzene and aniline ar removed, leaving 50.9 grams (0.52 mol)cuprous chloride as a residue in the still. The oily layer of thedistillate, which consists of aniline and benzene, is separated and usedfor,subsequent recoveries of copper chloride. The extracted ammoniumchloride solution, after distilling to remove traces of dissolvedbenzene and aniline, contains 0.4 gram of cuprous copper in solution.The solution is then treated with 0.215 gram of ammonium sulfide inaqueous solution, and the is removed by filtration. Upon evaporating thefiltrate to dryness, there is obtained 159 grams (2.97 mols) of pureammonium chloride.

Example 2 340 grams of an aqueous solution containing 13.1 grams (0.133mol) of cuprous chloride, 5.4

grams (0.04 mol) of cupric chloride and 53 grams (0.53 mol) of ammoniumchloride was agitated for two minutes. The mixture was then cooled to 10C. and the solid complex compounds of cupric and cuprous chlorides withaniline were removed by filtering. The aqueous ammonium chloridesolution collected as the'rlltrate contained only .23 gram of copper,calculated as metallic copper. More than 98 per cent of the copperchlorides originally present in the solution had been removed by thetreatment with aniline.

Example 3 200 c. c. of a 15,per cent aqueous solution of dimethylaminehydrochloride containing 5.96 grams (0.06 mol) of cuprous chloride wasshaken for one hour at ordinary room temperature with 17 grams (0.18mol) of aniline and the insoluble portion of the mixture separated fromthe aqueous portion. The aqueous portion was. analyzed and found tocontain 2.3 grams (0.023 mol) of copper. calculated as cuprous chloride.92.5 per cent of the copper was thus removed from the solution by thetreatment with aniline.

Other modes of applying the principle of the invention may be employedinstead of those explained, change being made as regards the methodherein disclosed, provides the step or steps stated by any of thefollowing claims or the equivalent of such stated step or steps beemployed.

. tinctly claim as our invention:

and dis- We thereiure particularly point out 1. In a method forseparating from one another a copper chloride and a hydrochloride of acompound selected from the class consisting of ammonia and aliphaticamines containing less than rated with ammonium sulfide, and removingpreipit t d pper sulfide. I

7. In av method for separating from one another a copper chloride andammonium chloride, which are contained in an aqueous solution there- ,ofthat is substantially free of uncombined amsix carbon atoms in themolecule, which are con-,

tained in an aqueous solution thereof that is substantially free ofuncombined ammonia and aliphatic amines, the steps which consist intreating the solution with an aryl-amine compound selected from theclass consisting of monoaryl amines and their hydrochlorides andseparating from the solutlon'the insoluble complex compound of thecopper chloride andarylamine compound thereby formed.

2. In a method for separating from one another a copper chloride andahydrochloride of a compound selected from the class consisting ofammonia and aliphatic amines containing less than six carbon atoms inthe molecule, which are contained in an aqueous'solution thereof that issubstantially free of uncombined ammonia and aliphatic amines, the stepswhich consist in treating the solution with an aryl-amine compoundselected from the class consisting of monoaryl amines and theirhydrochlorides, separating from.

the solution an insoluble complex compound of the copper chloride andarylamine compound, concentrating the remaining aqueous solution andrecovering therefrom said hydrochloride of a compound selected from theclass consisting of ammonia and aliphatic amines containing less thansix carbon atoms in the molecule.

3. In a method for separating from one another a copper chloride andammonium chloride, which are contained in an aqueous solution therev ofthat is substantially free of uncombined ammonia, the steps whichconsist in treating the solution with an arylamine compound selectedfrom the class consisting ofmonoaryl amines and their hydrochlorides,and separating from, the solution a complex compound of the copperchloride and arylamine compound. a

4. In a method for separating from one another a copper-chlorideandammonium chloride,

which are contained in an aqueous solution thereof that is substantiallyfree of uncombined ammonia, the steps which consist in treating thesolution with an arylamine compound selected from'the class consistingof monoaryl amines and their hydrochlorides, separating from thesolution an insoluble complex compound of. the copper chloride andarylamine compound, treating the aqueous solution from which the complexcom pound has been separated with ammonium sulfide and removingprecipitated copper. sulfide.

5. In a. method for separating from one another a copper chloride andammonium chloride,

which are contained in an aqueous solution there-- monia, the stepswhich consist in treating the solution with aniline hydrochloride andseparating from the solution an insoluble complex compound comprisinganiline and copper chloride.

8. In a method for separating from one another a copper chloride andammonium chloride, which are contained in an aqueous solution thereofthat is substantially free of uncombined ammonia, the steps whichconsist in treating the solution with aniline hydrochloride, separatingfrom the solution the insoluble complex compound comprising aniline andcopper chloride thereby formed, treating the aqueous solution fromwhich-the complex compound has been sep arated with ammonia in amountsufiicient to regenerate aniline from aniline hydrochloride re' mainingin the solution, separating the regenerated aniline from the solution,treating the solution from which the aniline has been separated withammonium sulfide, and removing pre-' cipitated copper sulfide.

'9. In a method for separating from one another cupric chloride andammonium chloride, which are contained in an aqueous solution thereofthat is substantially free of uncombined ammonia, the steps whichconsist in treating the solution with aniline, andseparating from thesolution the insoluble complex compoundof cupric chloride and anilinethereby formed.

10. In a method for separating from one another cupric chloride andammonium chloride, which are contained in an aqueous solution thereofthat is substantially free of uncombined ammonia, the steps whichconsist in treating the solution with at least 1 mol of aniline for eachmol of cupric chloride in the solution and separatingfrom the solutionthe complex compound of cupric chloride and aniline thereby formed.

11. In a method for separating from one an-.

other cuprouschloride'and ammonium chloride,

which are contained in an aqueous solution thereof that is substantiallyfree of uncombined ammonia,' the steps which consist in treating thesolution with aniline and separating from the solution the insolublecomplex compound of cuprous chloride and aniline thereby formed.

12.;In a method for separating from one another cuprous chloride andammonium chloride, which are contained in an aqueous solution thereofthat is substantially free of uncombined ammonia, the steps whichconsist in treating the solution with aniline, separating an insolublecomplex compound of cuprous. chloride and aniline, concentrating theremaining aqueous 'solution, and recovering ammonium chloride therefrom!13. In a method for separating from one another cuprous chloride andammonium chloride, which are contained in an aqueous solution thereofthat is substantially free of uncombined ammonia, the steps whichconsist in treating the solution with at least 1 mol of aniline for eachfrom the resulting aqueous solution, treating the solution from whichthe aniline has been sepamol of cuprous chloride in the solution, andseparating from the solution the insoluble complex compound of cuprouschloride and aniline thereby formed.

14. In a method for separating from one another cuprous chloride andammonium chloride, which are contained in an aqueous solution thereofthat is substantially free of uneombined ammonia, the stepswhich'consist in treating the solution with at least 1 mol of anilinefor each mol of cuprous chloride in the solution, separating from thesolution an insoluble complex compound of cuprous chloride and aniline,concentrating the remaining aqueous solution, and recovering ammoniumchloride therefrom.

15. In a method for separating from one another cuprous chloride andammonium chloride which are contained in an aqueous solution cipitate,as copper sulfide, traces of copper' remaining in the solution, removingthe precipitated copper sulfide, concentrating the resuitini solution,and recovering ammonium chloride therefrom.

16. In a method for separating from one another cuprous chloride andammonium chloride, which are contained in an aqueous solution thereofthat is substantially free of uncombined ammonia, the steps whichconsist in treating the solution under non-oxidizing conditions withbetween 1 and 10 mols of aniline for each moi of cuprous chloride in thesolution, and separating from the solution the insoluble complexcompound of cuprous chloride and aniline thereby formed.

NOLAND POF'FENBERGER.

RAY D. HOLMES.

